Semiconductor devices which are based on IGFET (insulated gate field effect transistor) cells may include subsurface structures including gate electrodes. For providing contacts to impurity zones formed in semiconductor mesas between the subsurface structures a photolithographic mask defining placement and size of contact openings for the contacts is aligned with a photolithographic mask defining placement and size of the subsurface structures. Alignment tolerances between the two photolithographic masks define a minimum distance between neighboring subsurface structures. Approaches replacing the mask lithography for the contact openings by a self-aligned contact regime allow for further reducing the distances between neighboring subsurface structures to exploit carrier confinement effects. It is desirable to provide semiconductor devices with small distances between neighboring subsurface structures in a reliable way.